U.S. Pat. No. 5,410,016 to Hubbell et al. discloses biocompatible, biodegradable macromers which can be polymerized to form hydrogels. The macromers are block copolymers that include a biodegradable block, a water-soluble block with sufficient hydrophilic character to make the macromer water-soluble, and one or more polymerizable groups. The polymerizable groups are separated from each other by at least one degradable group, Hubbell specifically discloses using polyhydroxy acids, such as polylactide, polyglycolide and polycaprolactone as the biodegradable polymeric blocks. One of the disclosed uses for the macromers is to plug or seal leaks in tissue.
Other hydrogels have been described, for example, in U.S. Pat. No. 4,938,763 to Dunn et al., U.S. Pat. Nos. 5,100,992 and 4,826,945 to Cohn et al., U.S. Pat. Nos. 4,741,872 and 5,160,745 to De Luca et al., U.S. Pat. No. 5,527,864 to Suggs et al., and U.S. Pat. No. 4,511,478 to Nowinski et al. Methods of using such polymers are described in U.S. Pat. No. 5,573,934 to Hubbell et al. and PCT WO 96/29370 by Focal.
While numerous references disclose using homopolymers and copolymers including carbonate linkages to form solid medical devices, such as sutures, suture coatings and drug delivery devices (see, for example, U.S. Pat. No. 3,301,824 to Hostettler et al., U.S. Pat. No. 4,243,775 to Rosensaft et al., U.S. Pat. No. 4,429,080 to Casey et al., U.S. Pat. No. 4,716,20 to Casey et al., U.S. Pat. No. 4,857,602 to Casey et al., U.S. Pat. No. 4,882,168 to Casey, EP 0 390 860 B1 by Boyle et al., U.S. Pat. No. 5,066,772 to Tang et al., U.S. Pat. No. 5,366,756 to Chesterfield et al., U.S. Pat. No. 5,403,347 to Roby et al. and U.S. Pat. No. 5,522,841 to Roby et al.), none of these publications discloses incorporating polymerizable groups on the polymers so that the polymers can be further polymerized. Accordingly, none of these polymers can be used in the same manner as the macromers in U.S. Pat. No. 5,410,016 to Hubbell et al.
Sealing or plugging holes in lung tissue is inherently more difficult than sealing other types of tissue because the tissue is constantly expanded and contracted during normal respiration. It would be advantageous to provide macromers which can be rapidly polymerized in vivo to form hydrogels which are more elastic than conventional hydrogels, for example, for use in sealing lung tissue.
It is therefore an object of the present invention to provide biodegradable, biocompatible macromers that can be rapidly polymerized in vivo to form hydrogels which are more elastic than conventional hydrogels.
It is a further object of the present invention to provide a macromer solution which can be administered during surgery or outpatient procedures and polymerized as a tissue adhesive, cell encapsulating medium, tissue sealant, wound dressing or drug delivery device.
It is a still further object of the present invention to provide a macromer solution which can be polymerized in vivo on a surface to be coated in a very short time frame to form conformal coating layers.